The present application relates to hyperechogenic needles and methods for making and using the same, and more specifically, but not exclusively, concerns a needle having a hyperechogenic particulate material affixed to an outer surface of the needle to improve ultrasonic imaging properties of the needle.
Ultrasonic imaging techniques, such as 2D ultrasound, are widely used in modern medicine for multiple applications. In addition to imaging physiological structures and tissue such as nerves, organs, tumors, vessels, and the like, it is often desirable for a physician or technician to have an image of a medical device which has been inserted into the tissue or passageway of a patient. The types of devices that are surgically sterilized and inserted into patients are many. Typical examples include: needles, catheters and a variety of other medical products such as stents, dilators, pacing leads, introducers, angiography devices, angioplasty devices, pacemakers, inpatient appliances such as pumps and other devices. Ultrasound allows the practitioner to view anatomical structures in real time, which allows for greater precision in a given procedure.
One example of a technique that benefits from the use of 2D ultrasound is a needle biopsy technique, in which accurate placement of a needle tip in a specific target position is critical. Another example is peripheral nerve blockage, in which ultrasound imaging allows the clinician to view the nerve to be blocked in real time for accurate positioning of the needle tip. In using a 2D ultrasound apparatus to position a needle tip, the clinician is able to see below the skin, and thereby view the location of the needle tip relative to surrounding tissues. This renders greater precision in the procedure, and allows the clinician to advance the needle to the desired position relative to the tissues. In the case of peripheral nerve blockage, a local anesthetic can then be deposited near the nerve to be blocked.
Ultrasound energy comprises high frequency sound waves generated in the 2 to 15 MHz range. In common medical practice, a range of 5 to 12 MHz is employed for most applications, as this range provides optimal tissue resolution and penetration. The sound waves are commonly generated using a piezoelectric crystal. Piezoelectric crystals produce ultrasound energy when electrically stimulated, and also respond to reflected ultrasound energy. The ultrasound energy is pulsed and time locked. Ultrasound energy is typically reflected, and this reflected ultrasound energy is capable of amplification. Measuring reflected amplified energy enables the clinician to determine a range or distance to a tissue interface. Medical ultrasound techniques, such as 2D medical ultrasound, typically employ a piezoelectric effect reflective head, a computer, an electronic component, and a monitor to display the anatomy generated by the ultrasound integration of the tissue being examined.
An ultrasound head used in a typical 2D ultrasound technique includes a set of piezoelectric crystals in alignment, which crystals can be electronically switched on or off to respond to reflected ultrasound energy. The time delay between ultrasound emission and reflection can be used to construct a 2D picture of the tissue in alignment in the ultrasound plane generated. When the piezoelectric crystals are switched on and off electronically, a planar picture of the anatomy is created and displayed on the 2D ultrasound monitor. The 2D ultrasound apparatus allows tissue and anatomy to be visualized in both the axial and lateral direction. By controlling the switching order and timing of the individual piezoelectric crystals in the ultrasound head, the tissue can be scanned in a temporal fashion, thus creating a real time display of the tissue, and thus motion.
One major shortcoming of the use of a conventional needle in a 2D ultrasound technique is that the needle is often not easily visible in the plane of the 2D ultrasound beam. Maximum reflection of ultrasound energy occurs when the needle is at a 90° angle to the direction of the ultrasound waves in the 2D ultrasound plane. The signal degrades as this angle is reduced, to a point at which the needle becomes invisible in the 2D ultrasound plane. The ability to resolve a needle image on a 2D ultrasound monitor degrades as the needle moves from the 90° orientation to a lesser orientation, at which point it becomes invisible on a 2D monitor. This phenomenon is caused by specular reflectance, as the surface of the needle will only reflect ultrasound waves directly back to the ultrasound head. This reflectance is generally similar to the way that light is reflected from a mirror. The specular reflectance of the needle makes needle visualization with 2D ultrasound difficult. Commonly, the needle is invisible as it is advanced, greatly decreasing the utility of 2D ultrasound for determining needle tip placement. This effect makes use of 2D ultrasound in the placement of a needle problematic, since it is often ergonomically difficult to align it in the ultrasound head, define the tissue anatomy, and advance the needle in a 3D structure, while keeping the needle in view on the narrow 2D ultrasound plane.
To address concerns relating to decreasing the invasiveness of the procedures and improving patient outcomes, various approaches have been used to enhance ultrasonic imaging by modifying the reflective surface characteristics of needles and other devices. Optimal visualization of anatomical structures using 2D ultrasound reduces the likelihood of a practitioner misplacing the tip of a needle and reduces the number of attempts that would otherwise be necessary to accurately place the tip of a needle, decreasing the risk of inadvertent trauma to surrounding structures, such as, for example, accidental puncture of a blood vessel or accidental damage to a nerve.
A variety of approaches have been proposed to improve the echogenicity of needles and other medical devices; however, there is a need for provision of further improvement relating to the visualization of needles and other medical devices using two-dimensional ultrasound to provide accurate placement and monitoring of a surgical instrument such as a needle inserted into the body, which does not require a specific angle of orientation, and which is inexpensive to manufacture. The present application addresses this need.